Slaughtering equipment, particularly for smaller-scale operations, need not
be elaborate and expensive. The amount of equipment will depend on the
slaughtering procedures employed. If possible, all equipment should be
made of stainless steel or plastic, be rust resistant and easily cleaned and
sanitized. Equipment which does not get in contact with the meat (e.g.
overhead rails, working platforms, knocking pen) is usually made of
galvanized steel.

block and tackle or chain hoist strong enough to hold the weight of the
animal to be slaughtered

pritch, chocks or skinning rack (dressing cradle)

a strong beam, tripod or track 2.4 to 3.4 m from floor

spreader - gambrel or metal pipe

several buckets

working platforms

scalding barrel or tank

pot, barrel or system for boiling water

bell scrapers

solid scraping table or platform

thermometer registering up to 70°C

hog or hay hook

torch or flame for singeing

The last seven items indicate additional equipment required when hogs
are scalded and scraped rather than skinned.

Useful additional equipment:

knocking pen

bleeding hooks (for vertical bleeding)

blood-catching trough

wash trough (tripe)
Sanitation of hands and tools:

hand wash-basin

implement sterilizers

Means should be available to clean thoroughly all equipment coming into
contact with carcasses or meat. Implement sterilizers are stainless-steel
boxes holding hot (82°C) water, shaped to suit particular equipmentknives,
cleavers, saws, etc. (Fig. 2). Knife sterilizers should be placed in
positions where every operator who uses a knife has immediate access.
Handles as well as blades must be sterilized. Each operator should have at
least two knives etc., one to use while the other sterilizes (Figs 10 and 11).

Failure to sterilize all knives and equipment regularly will result in carcass
contamination. Bacteria will be transferred from the hide to the carcass and
from carcass to carcass (Fig. 12).

Stress in its many forms, e.g. deprivation of water or food, rough handling,
exhaustion due to transporting over long distances, mixing of animals
reared separately resulting in fighting, is unacceptable from an animal
welfare viewpoint and should also be avoided because of its deleterious
effects on meat quality. The most serious consequence of stress is death
which is not uncommon among pigs transported in poorly ventilated,
overcrowded trucks in hot weather. From loading on the farm to the stunning
pen animals must be treated kindly, and the lorries, lairages and equipment
for livestock handling must be designed to facilitate humane treatment.
Stress immediately prior to slaughter, such as fighting or rough handling in
the lairage, causes stored glycogen (sugar) to be released into the
bloodstream. After slaughter this is broken down in the muscles producing
lactic acid. This high level of acidity causes a partial breakdown of the
muscle structure causing the meat to be pale, soft and exudative (PSE). This
condition is mostly found in pigs.

10. Plastic (right) handles are
more hygienic than wooden (left)
for knives and other equipment.
Note the excessively worn knife
(third from left) which should be
discarded

12. Poor hygiene during
carcass dressing causes
the spread of bacteria
from the skin of the
carcass to knives and to
operators' hands

11. Knives and
other equipment
should be kept
sharp and in good
repair

Long-term stress before slaughter such as a prolonged period of fighting
during transport and/or lairage leads to exhaustion. The sugars are used up
so that less is available to be broken down and less lactic acid is produced.

The reduced acidity leads to an abnormal muscle condition known as
dark, firm and dry (DFD) in pigs or dark cutting in beef. The condition is
rarer in lamb. Such meat has a high pH (above 6.0) and spoils very quickly
as the low acidity favours rapid bacterial growth.

Handling animals during transport and lairage

An electric goad (Fig. 13) should be used rather than a stick or tail-twisting
not only to avoid stress but also to prevent carcass bruising. Grabbing sheep
by the fleece also causes bruising (Fig. 14).

To avoid fighting, animals not reared together must not be mixed during
transport and lairage. Load and unload using shallow stepped ramps to
avoid stumbles. Trucks should be neither over- nor underloaded.
Overloading causes stress and bruising due to crushing. Underloading
results in animals being thrown around and falling more than necessary.
Drivers should not corner at excessive speed and must accelerate and
decelerate gently.

The lairage should have small pens. Corridors must curve and not bend
sharply so that stock can see a way forward. Stock must not be slaughtered
in sight of other stock. Plenty of clean water must be available. The lairage
must be well lit and ventilated. Do not hold stock in lairage for more than
a day. Only fit, healthy stock may be slaughtered for human consumption.

Fasting before slaughter reduces the volume of gut contents and hence
bacteria and therefore reduces the risk of contamination of the carcass
during dressing. It is usually sufficient for the animals to receive their last
feed on the day before slaughter. Stock should have a rest period after arrival
at the slaughterhouse. However, long periods in the lairage can lead to DFD
if the animals are restless and fighting or mounting.

Animals should be as clean as possible at slaughter. Producers should
wash their animals before leaving the farm. Trucks used for transport must
be washed after each load and the lairage at the slaughterhouse should be
kept clear of faecal matter and frequently washed (Figs 15 and 16).

Most countries have legislation requiring that animals are rendered
unconscious (stunned) by a humane method prior to bleeding. Exceptions
are made for religions which require that ritual slaughter without prior
stunning is practised, provided the slaughter method is humane. Stunning
also makes sticking (throat-slitting) less hazardous for the operator. The
animal must be unconscious long enough for sticking to be carried out, and
for brain death to result from the lack of blood supply.

13. An electric goad delivers a
small electric current via two
electrodes to encourage
animals to move. It avoids
stress and carcass damage

15. Trucks must be thoroughly
washed after each load

14. Unsightly bruising caused by
striking the animal with a stick.
This not only causes loss of
product but is also inhumane

16. Pens will need washing
after emptying

Methods of stunning

Direct blow to skull using a club or poleaxe. The blow must be dealt with
precision and force, so that the skull is immediately smashed, causing
instantaneous unconsciousness. In cattle the aiming point is in the middle
of the forehead in line with the ears, where the skull is thinnest. Horses have
thinner skulls and are therefore easier to stun by this method. In sheep and
goats the brain is more easily reached from the back of the neck. Pigs have
a well-developed frontal cavity so the blow should be aimed slightly above
the eyes.

Slaughtering mask. A bolt held in the correct position by the mask is
driven into the animal's brain by a hammer blow. The device is usually fitted
with a spring which returns the bolt to its original position.

Free bullet fired from a pistol into the skull is effective but unsafe. This
method has been used on horses and cattle.

Captive-bolt pistols fitted with a blank cartridge are effective on cattle and
sheep but not pigs whose skulls are thicker (Figs 17 and 18). After firing,
the bolt returns to its original position in the pistol. The bolt may or may not
be designed to penetrate the skull. With penetrating types the brain becomes
contaminated with hair, dirt and bone fragments. If brains are to be saved as
edible tissue then the non-penetrating type with a mushroom-shaped head
should be used.

Electrical stunning. An electric current of high frequency but, in the case
of manually operated equipment, of relatively low voltage (60–80 V) is
passed through the brain of an animal for a few seconds to produce
unconsciousness. If applied correctly a deep state of unconsciusness is
invariably achieved. Strict safety rules must be observed. Head tongs (Fig.
19) are suitable for pigs and sheep but not for cattle. The electrodes carried
on the ends of the tongs must be accurately placed (Figs 20 and 21). Places
where the skull is thick must be avoided. Electrical contact is impeded by
hair and caked mud. Water or brine will improve contact but the head must
not be completely wet otherwise the current will have a short-circuit path
avoiding the brain. The electrodes must be applied with strong pressure.

19. Head tongs are used to stun pigs
and sheep electrically but are not suitable for cattle. The electrode on the
end of each tong is ridged for better contact

17. Captive-bolt stunner suitable for cattle

20. The electrodes must be applied firmly to either side of the head so that the electrical current passes through the brain causing
unconsciousness in a few seconds

21. Head tongs are also suitable for stunning pigs

18. Aiming point for stunning cattle

Carbon dioxide stunning is used only in large pig abattoirs. Pigs are
induced into a chamber and exposed to a concentration of 85 percent CO2
for about 45 seconds. Although effective for anaesthetizing sheep, it is
impractical because of large amounts of CO2 collecting in the wool and
affecting operators on the killing line.

Bleeding after stunning

The objectives of bleeding are to kill the animal with minimal damage to the
carcass and to remove quickly as much blood as possible as blood is an ideal
medium for the growth of bacteria.

Sticking, severing the major arteries of the neck, should immediately
follow stunning. Care must be taken not to puncture the chest cavity or it will
fill with blood.

22. Immediately following stunning the animal is hoisted by one leg and stuck. For sheep the sticking
point is in the side of the neck, the gash cut severing all the major blood vessels in a single movement

23. The sticking point for
pigs is in the centre of the neck just in front of the breastbone

Cattle. Insert the sticking knife carefully just above the breastbone at 45°
pointed toward the head. Ensure that the carotid arteries and jugular veins
are severed in one movement.

Sheep. Draw the knife across the jugular furrow close to the head severing
both carotid arteries. Alternatively, the knife may be inserted through the
side of the neck, though this requires more skill (Fig. 22).

Pigs. As for cattle but do not go in too far or a pocket of blood will collect
at the shoulder (Fig.23). To reduce contamination by the scalding tank water
the cut should be as small as possible.

Bleeding on a rail

The most hygienic system of bleeding and dressing is to shackle the animal
immediately after stunning, then hoist it on to a moving rail. The animal is
stuck while being hoisted to minimize the delay after stunning. Bleeding
continues until the blood flow is negligible when carcass dressing should
begin without further delay (Fig. 24)

Blood for human use must be collected with special equipment to avoid
contamination from the wound, the gullet of the knife. A hollow knife
directs blood away from the wound into a covered stainless-steel container
without touching the skin or hide. The knife may be connected to a hose to
reduce the risk of contamination. The hose may even be connected to a pump
to speed the blood flow. Between 40 and 60 percent of the total blood
volume will be removed though this will be reduced if sticking is delayed.
To prevent coagulation, citric acid solution made up with one part citric acid
to two parts water is added at a rate up to 0.2 percent of the blood volume.
The main sources of contamination during sticking and bleeding include the
knife, the wound and the food-pipe. The knief should be changed after each
operation and returned to a sterilizer. Cutting the hide of sheep and cattle and
opening out to make a clean entry for the sticking knife reduces
contamination from the wound. If the food-pipe is pierced semi-digested
food may be regurgitated contaminating the blood and neck wound.

Horizontal bleeding

Horizontal bleeding is claimed to give faster bleeding rates and a greater
recovery of blood. This may be due to certain organs and blood vessels being
put under pressure when animals are hoisted, thus trapping blood and
restricting the flow. Bleeding on the floor is very unhygienic. The operation
should take place on a specially designed, easily cleaned stainless-steel
table which should be cleaned frequently. If blood is to be saved it must not
come in contact with the table before reaching the collecting vessel.

24. After sticking, the
animal should be left
to bleed until the
blood flow becomes
negligible

25. Scalding/dehairing tank
which accommodates four
pigs: one awaiting
immersion, two immersed
and one just completing
immersion. When the bars
are rotated the pigs change
position

26. After immersion
any remaining loose
hairs are scraped
from the skin

27. Simple tank for
combined scalding/
dehairing. The tank is
filled with water at
60°C, a pig is lowered
in, the lid is closed
and the paddles
rotate, the rubber tips
loosening the hairs

Bleeding without stunning

The Jewish and Muslim religions forbid the consumption of meat which
was killed by any method other than bleeding. Since it is difficult to
guarantee that all animals will recover consciousness after being stunned by
any particular method, stunning is not generally allowed. There are
exceptions, however. Some communities do accept low-voltage electrical
stunning.

Because animals are fully conscious at the time of sticking, ritual
slaughter may be less humane than sticking after stunning. To reduce the
suffering operators must be highly skilled so that a successful gash cut
severing all the veins and arteries is made quickly at the first attempt.
Different communities have different regulations as to the orientation of the
animal at sticking, some favouring a position lying on its side, others
insisting it lie on its back. The animal should not be hoisted until
unconsciousness due to lack of blood supply to the brain is complete.

Scalding in water at around 60°C for about six minutes loosens the hair in
the follicle. Too low a temperature and the hair will not be loosened and too
high a temperature and the skin will be cooked and the hair difficult to
remove. The simplest equipment consists of a tank into which the pig is
lowered by a hoist. The water is heated by oil, gas, electricity or an open
steam-pipe.

To check the effectiveness of the scald, rub the skin with the thumb to see
if hair comes away easily. Some machines have the thermostatic controls and
timers. To reduce contamination, scalding water should be changed
frequently, pigs should be as clean as possible at sticking, and bleeding
should be fully completed before immersion.

In large factories pigs are transported through scalding tanks with rotating
bars (Fig. 25) or through long scalding tanks stretching from the sticking
point to the dehairing point in the time required for an effective scald.

Dehairing is done with a specially formed scraper (bell scraper or knife).
If the scald is effective all the hair can be removed by this manual method
(Fig. 26). Another simple method is to dip the pig in a bath containing a hot
resin adhesive. The pig is removed from the bath and the resin allowed to
set partially when it is peeled off pulling the hair with it from the root. This
is less labour-intensive than scraping and produces a very clean skin. After
use the adhesive is melted again, strained to remove the hair and returned
to the tank.

Another method of removing dirt and hair in one operation is to skin the
carcass though this is only done when the skin is required for leather goods.

With the simple scalding tank, dehairing and scalding may be combined
in one operation. Inside the tank are rotating rubber-tipped paddles which
are started after closing the lid. As the hair is loosened by the scalding water
it is removed by the rubbing effect of the paddles against the skin (Fig. 27).

Singeing removes any remaining hairs, shrinks and sets the skin,
decreases the number of adhering micro-organisms and leaves an attractive
clean appearance. It may be done with a hand-held gas torch (Fig. 28).
Automated systems transport the pig into a furnace and leave it long enough
for an effective singe.

After singeing, black deposits and singed hairs are scraped off (Fig. 29)
and the carcass is thoroughly cleaned before evisceration begins.

The outer side of the hide must never touch the skinned surface of the
carcass. Operators must not touch the skinned surface with the hand that was
in contact with the skin.

Combined horizontal/vertical methods

Head. After bleeding, while the animal is still hanging from the shackling
chain, the horns are removed and the head is skinned. The head is detached
by cutting through the neck muscles and the occipital joint. Hang the head
on a hook (Fig. 30). Lower the carcass on its back into the dressing cradle.

Legs. Skin and remove the legs at the carpal (foreleg) and tarsal (hind leg)
joints. The forelegs should not be skinned or removed before the carcass is
lowered on to the dressing cradle or the cut surfaces will be contaminated.
The hooves may be left attached to the hide.

28. After scraping away loose hairs any remaining hairs can be singed and the skin set with a
hand-held gas torch

30. The head is completely skinned and hung on a hook to
await inspection

29. A special knife, the black scrape, is used to scrape off any singed hairs
and black deposits

32. In the combined horizontal/
vertical dressing method the carcass is lowered on to a cradle, the legs, brisket and
flanks are skinned, then the carcass is raised to the half-hoist position. Note that this is
much less hygienic than verticaldressing on a rail

33. Note the possible contamination of the carcass by the intestines and the hide
dragging on the floor in the combined horizontal/vertical dressing method

31. Correct cutting lines for hide removal

Flaying. Cut the skin along the middle line from the sticking wound to the
tail. Using long firm strokes and keeping the knife up to prevent knife cuts
on the carcass, skin the brisket and flanks, working backwards toward the
round (Fig. 31). Skin udders without puncturing the glandular tissue and
remove, leaving the supermammary glands intact and attached to the
carcass. At this point raise the carcass to the half-hoist position, the
shoulders resting on the cradle and the rump at a good working height (Figs
32 and 33).

Clear the skin carefully from around the vent (anus) avoiding puncturing
it and cut the abdominal wall carefully around the rectum. Tie off with twine
to seal it. Skin the tail avoiding contamination of the skinned surface with
the hide. Raise the carcass free of the floor and finish flaying.

Vertical methods

High-throughput plants have overhead rails which convey the carcass from
the sticking point to the chills. Hide removal is carried out on the hanging
carcass (Figs 34, 35 and 36). The operations are as in the combined
horizontal/vertical method, but as it is not possible to reach the hide from
ground level more than one operator is needed. A single operator may work
with a hydraulic platform which is raised and lowered as required.

Automatic hide pullers are used in high-throughput slaughterhouses.
Some types pull the hide down from the hind, others from the shoulders
upwards toward the rump.

Automation of hide removal reduces contamination since there is less
handling of the carcass and less use of knives. Moving overhead rails also
improve hygiene by reducing carcass contact with operators, equipment
such as dressing cradles and with each other since carcasses are evenly
spaced.

Small ruminants

Sheep fleeces can carry large volumes of dirt and faeces into the
slaughterhouse. It is impossible to avoid contamination of sheep and lamb
carcasses when the fleece is heavily soiled. The fleece or hair must never
touch the skinned surface, neither must the operator touch the skinned
surface with the hand that was in contact with the fleece.

34. The leg is freed from the
skin and the hock cut off

35. Pneumatically operated rotating knives (flayers) speed the removal of the hide from the flanks

36. Flaying knives are used for the more intricate parts of hide removal

Combined horizontal/vertical method

The animal is turned on its back and cuts are made from the knuckles down
the forelegs. The neck, cheeks and shoulders are skinned. The throat is
opened up and the gullet (food-pipe) is tied off (see Fig. 41). The skin on the
hind legs is cut from the knuckles down to the tail root. The legs are skinned
and the sheep is hoisted by a gambrel inserted into the Achilles tendons. A
rip is made down the midline and skinning proceeds over the flanks using
special knives or the fists (see Fig. 39). The pelt is then pulled down over
the backbone to the head. If the head is for human consumption it must be
skinned or it will be contaminated with blood, dirt and hairs.

Moving cratch and rail system. The hanging carcass is lowered on to a
horizontal conveyor made up of a series of horizontal steel plates, bowed
slightly and divided into sets large enough to cradle a single animal. Two
operators usually work together on each lamb performing the legging
operations and opening the skin to the stage where it can be pulled off the
back. When the gambrel is inserted into the hind legs it is hoisted on to a
dressing rail.

Vertical method

At sticking the animal is shackled by one hind-leg and left to bleed. Dressing
commences with the free leg which is skinned and the foot removed (Fig.
37). A gambrel is inserted into this leg and hung on a runner on a dressing
rail. The second leg is freed from the shackle, skinned and dressed, then
hooked on to the other end of the gambrel. The skin is opened down the
midline and cleared from the rump.

A spreader frame (a bar U-shaped at each end) spreads the front legs to
simplify work on the neck, breast and flanks. The front toes are held in each
end of the frame which is then slung up on to a separate travelling hook. The
animal is therefore suspended by all four legs belly uppermost (Figs 38 and
39). Skinning continues as in the combined horizontal/vertical method. To
clear the shoulders and flanks, the forelegs are freed from the spreader and
the feet removed, the animal returning to a vertical position. The skin can
now be completely pulled off (Fig. 40), including the head if this is for
consumption, though this takes some work with the knife. In both methods,
after fleece removal the vent and food-pipe are cleaned and tied off (Fig.41).

37. Fleece removal starts with skinning the free hind leg. Care must be taken to
avoid the hide touching the skinned surface or the carcass will be contaminated
with faecal matter

38. With forelegs in a spreader frame and hind legs in a gambrel, the sheep is suspended in a
horizontal position

40. After skinning the neck and
breast, the front legs are freed and skinning continues in the vertical position with the flanks and back

39. The fists can be used to clear the fleece from the breast

41. After skinning the neck, the food-pipe is freed and tied off to
prevent regurgitation of stomach contents

With all species care must be taken in all operations not to puncture the
viscera (Fig. 42). All viscera must be identified with the carcass until the
veterinary inspection has been passed. After inspection the viscera should
be chilled on racks etc. for better air circulation (Fig. 43).

Cattle

The brisket is sawn down the middle (Fig. 44). In the combined horizontal/
vertical system this is done with the animal resting on the cradle. The carcass
is then raised to the half-hoist position and when hide removal is complete
the abdominal cavity is cut carefully along the middle line. The carcass is
then fully hoisted to hang clear of the floor so that the viscera fall out under
their own weight (Fig. 45). They are separated into thoracic viscera, paunch
and intestines for inspection and cleaning (Figs 46 and 47). If any of the
stomachs or intestines are to be saved for human consumption, ties are
made at the oesophagus/stomach, stomach/duodenum boundaries, the
oesophagus and rectum having been tied off during hide removal. This
prevents cross-contamination between the paunch and the intestines.

Small ruminants

A small cut is made in the abdominal cavity wall just above the brisket, and
the fingers of the other hand are inserted to lift the body wall away from the
viscera as the cut is continued to within about 5 cm of the cod fat or udder.

The omentum is withdrawn, the rectum (tied off) loosened, and the viscera
freed and taken out. The food-pipe (tied off) is pulled up through the
diaphragm. The breastbone is split down the middle taking care not to
puncture the thoracic organs which are then removed.

Pigs

Loosen and tie off the rectum. Cut along the middle line through the skin and
body wall from the crotch to the neck (Fig. 48). Cut through the pelvis and
remove the bladder and sexual organs. In males the foreskin must not be
punctured as the contents are a serious source of contamination. All these
organs are considered inedible.

42. When cutting through the abdomen wall, if the viscera are punctured their contents will
severely contaminate the carcass

43. A portable rack suitable for hanging offal for chilling

44. A mechanical saw
speeds the splitting of
the brisket but care
must be taken not to
puncture the viscera

45. After carefully cutting the abdominal wall along the midline the viscera fall out under their
own weight

46. A suitable receptacle should catch the viscera so that they
are not contaminated by contact with the floor

47. A portable cart
suitable for catching
cattle stomachs and
intestines with a
separate tray for edible
offal such as liver,
heart and lungs

Remove the abdominal and thoracic viscera intact. Avoid contact with the
floor or standing platform.

The kidneys are usually removed after the carcass has been split down the
backbone. The head is usually left on until after chilling.

Work facing the back of the carcass. Split the carcass down the backbone
(chine) with a saw or cleaver from the pelvis to the neck (Figs 49 and 50).
Sawing gives a better result but bone dust must be removed (Fig. 51). If a
cleaver is used, it may be necessary to saw through the rump and loin in older
animals.

The saw and cleaver should be sterilized in hot (82°C) water between
carcasses. Power saws increase productivity.

48. The body wall is split down
the midline taking care not to
puncture the viscera

51. Carcasses should be spray-washed
to remove visible staining, paying
particular attention to bone dust and the
internal surface, but without using
excessive amounts of water

50. Hand-saws are
much slower than
mechanical saws
though they are
preferable to cleavers
which splinter bones

Pigs

These are suspended and are split down the backbone as for cattle, but the
head is generally left intact (Fig. 94).

Sheep

Sheep and lamb carcasses are generally sold entire. If necessary they can be
split by saw or cleaver, but a saw will probably be necessary for older
animals.

Carcass washing

The primary object of carcass washing is to remove visible soiling and blood
stains and to improve appearance after chilling (Fig. 51). Washing is no
substitute for good hygienic practices during slaughter and dressing since
it is likely to spread bacteria rather than reduce total numbers. Stains of gut
contents must be cut off. Wiping cloths must not be used.

Carcass spraying will remove visible dirt and blood stains. Water must be
clean. Soiled carcasses should be sprayed immediately after dressing before
the soiling material dries, thus minimizing the time for bacterial growth.
Under factory conditions bacteria will double in number every 20 or 30
minutes.

In addition to removing stains from the skinned surface, particular
attention should be paid to the internal surface, the sticking wound and the
pelvic region.

A wet surface favours bacterial growth so only the minimum amount of
water should be used and chilling should start immediately. If the cooler is
well designed and operating efficiently the carcass surface will quickly dry
out, inhibiting bacterial growth.

Bubbling of the subcutaneous fat is caused by spraying with water at
excessively high pressure, which may be due to the pressure in the system
or a result of holding the spray nozzle too close to the carcass.

Carcass dressing

The object of carcass dressing is to remove all damaged or contaminated
parts and to standardize the presentation of carcasses prior to weighing.
Specifications will differ in detail for different authorities. Veterinary
inspection of carcasses and offal can only be carried out by qualified
personnel. Where signs of disease or damage are found the entire carcass and
offal may be condemned and must not enter the food chain, but more often
the veterinarian will require that certain parts, for instance those where
abscesses are present, be removed and destroyed. Factory personnel must
not remove any diseased parts until they have been seen by the inspector
otherwise they may mask a general condition which should result in the
whole carcass being condemned. Any instructions from the inspector to
remove and destroy certain parts must be obeyed.

Carcasses should go into the cooler as soon as possible and should be as dry
as possible. The object of refrigeration is to retard bacterial growth and
extend the shelf-life. Chilling meat post-mortem from 40°C down to 0°C
and keeping it cold will give a shelf-life of up to three weeks, provided high
standards of hygiene were observed during slaughter and dressing.

Carcasses must be placed in the cooler immediately after weighing. They
must hang on rails and never touch the floor (Fig. 52). After several hours
the outside of a carcass will feel cool to the touch, but the important
temperature is that deep inside the carcass. This must be measured with a
probe thermometer (not glass), and used as a guide to the efficiency of the
cooling.

52. Sheep carcasses
in the chill-room,
hung on rails clear of
the floor and spaced
to allow air
circulation to speed
drying

The rate of cooling at the deepest point will vary according to many factors
including the efficiency of the cooler, the load, carcass size and fatness. As
a general guide a deep muscle temperature of 6–7° C should be achieved in
28 to 36 hours for beef, 12 to 16 hours for pigs and 24 to 30 hours for sheep
carcasses. Failure to bring down the internal temperature quickly will result
in rapid multiplication of bacteria deep in the meat resulting in off-odours
and bone-taint.

High air speeds are needed for rapid cooling but these will lead to
increased weight losses due to evaporation unless the relative humidity
(RH) is also high. However, if the air is near to saturation point (100 percent
RH) then condensation will occur on the carcass surface, favouring mould
and bacteria growth. A compromise between the two problems seems to be
an RH of about 90 percent with an air speed of about 0.5 m/second.
Condensation will also occur if warm carcasses are put in a cooler partially
filled with cold carcasses.

The cooler should not be overloaded beyond the maximum load specified
by the manufacturers and spaces should be left between carcasses for the
cold air to circulate. Otherwise cooling will be inefficient and the carcass
surface will remain wet, favouring rapid bacterial growth forming slime (see
below).

Once filled, a cooler should be closed and the door opened as little as
possible to avoid sudden rises in temperature. When emptied, it should be
thoroughly washed before refilling. Personnel handling carcasses during
loading and unloading operations should follow the strictest rules regarding
their personal hygiene and clothing and should handle carcasses as little as
possible.

Marketing of meat under refrigeration

Chilled meat must be kept cold until it is sold or cooked. If the cold chain
is broken, condensation forms and microbes grow rapidly. The same rules
about not overloading, leaving space for air circulation, opening doors as
little as possible and observing the highest hygiene standards when handling
the meat apply. An ideal storage temperature for fresh meat is just above its
freezing point, which is about - 1°C (- 3°C for bacon because of the presence
of salt). The expected storage life given by the International Institute of
Refrigeration of various types of meat held at these temperatures is as
follows:

Type of meat

Expected storage life at - 1°C

Beef

up to 3 weeks (4–5 with strict hygiene)

Veal

1–3 weeks

Lamb

10–15 days

Pork

1–2 weeks

Edible offal

7 days

Rabbit

5 days

Bacon

4 weeks (at - 3°C)

Under commercial conditions, meat temperatures are rarely kept at - 1°C
to 0°C, so actual storage times are less than expected. The times would also
be reduced if RH were greater than 90 percent.

Meat should be placed in the refrigerator immediately following receipt.
Any parts which show signs of mould growth or bacterial slime should be
trimmed off and destroyed. Hands must be thoroughly washed after
handling such trimmings and knives must be sterilized in boiling water. The
refrigerator should be thoroughly cleaned after finding such meat and
should also be cleaned on a regular basis.

Carcasses, quarters and large primals should not be cut into smaller
portions before it is necessary as this will expose a greater surface area for
bacteria to grow. Freshly cut surfaces are moist and provide a better medium
for bacterial growth than the desiccated outer surfaces of cuts that have been
stored for some time.

An accurate thermometer should be placed in the refrigerator and checked
regularly. The temperature should remain within a narrow range (0° to
+ 1°C).

Transport of meat

Vehicles for transporting meat and carcasses should be considered as an
extension of the refrigerated storage. The object must be to maintain the
meat temperature at or near 0°C. Meat should be chilled to 0°C before
loading. Meat should hang on rails, not on the floor. If stockinettes are put
on carcasses they must be clean. Meat trucks should not carry anything other
than meat.

The refrigeration is usually produced by injecting liquid nitrogen or
carbon dioxide (CO2) into the compartment or by blowing air over CO2
chunks (dry ice). The temperature in these vans can be set and controlled to
minimize the temperature rise and to avoid condensation on the meat surface
(Fig. 53).

Insulated vans without refrigeration may be refrigerated by adding dry
ice. While this is a reasonably good alternative to the refrigerated truck it
does not allow the temperature to be controlled.

Uninsulated vans and open trucks should not be considered as suitable
transport for meat, particularly in hot climates. In addition to the
temperature abuse, condensation will occur when the meat goes back into
refrigeration, and in open trucks the meat is exposed to attack from insects.
Loading and unloading should be done quickly. If there are any unavoidable
delays then dry-ice blocks should be placed in the partly filled van.

53. Insulated vans with
refrigeration units should be
used for transporting meat

Carcass and meat handling and marketing without refrigeration

Where refrigeration is unavailable either owing to financial or technical
reasons (e.g. no power supply), the shelf-life of meat is reduced to days or
hours, not weeks. Slaughter and dressing must be near the point of sale and
it must be quick and clean. If carcasses and meat are kept in well-insulated
rooms, the temperature can be reduced with dry-ice blocks, if these are
available. Since it is easier to chill boneless cuts rather than whole carcasses,
hot-boning should be considered.

Stock must be handled carefully to avoid producing high-pH meat which
will spoil more quickly. Rooms used for slaughter and handling meat must
be clean and well ventilated, but out of direct sunlight, dust-free and verminfree
(rodents and insects). Hot water (82°C) must be available to clean all
equipment and surfaces and personnel must work very hygienically.
Receive all blood into sealed containers and have separate skips on wheels
for hooves, skins, green offal and trimmings.

54. Processing and
packing of offal must
be done in a room
separated from the
slaughter hall or other
meat-handling
facilities

Dressing on a vertical hoist will minimize contamination by floor or
cradle contact. Let nothing drop on the floor, only into skips. Personal
hygiene must be scrupulous. Any spills of gut contents on to the meat should
be cut off, but careful work will avoid this. The dressed carcass should be
hung on rails. If beef is quartered to facilitate handling, the cut surface is at
risk.

Red offal should be hung on hooks. Any offal processing must be in rooms
away from meat-handling facilities (Fig. 54). Intestines for human
consumption must be thoroughly cleaned and washed.

Storage and transport without refrigeration

Meat should be put on sale within a day of slaughter. If it has to be held it
should be hung in a clean, well-lit hall with good ventilation. Insects,
rodents and birds must be kept out, dust must not blow in. Trays of offal
should be on shelves, not on the floor. Barrows for wheeling carcasses and
quarters are better than carrying on shoulders, as they can be cleaned
frequently. All staff must wear clean clothing and observe strict personal
hygiene. Transport of non-refrigerated meat is very hazardous. If meat is to
be put in stockinettes and sacks these must be very clean. Meat should be
on rails in the truck or wagon, and it is not advisable to carry it more than
a day's journey before sale.